European Article Number test

Question

I wanted to do a simple program to test if the check digit (?) is true, but i get error messages during compiling and i have no idea how to fix that.
import java.applet.*; import java.awt.*; import java.awt.event.*; import java.io.*;
public class ean1 extends applet implements ActionListener{
         String muh = new String();
         TextField eingabe = new TextField(" ", 13);
         muh = eingabe.getText();
         Label ausgabe = new Label("_____");
         int k = muh.length();
         int posGew = 3;
         int ProdWert = 0;
         int ProdZiffern = 0;
         while (k>0){
                     String buchst = muh.substring(k-1,k);
                     int aktZiffer = Integer.valueOf(buchst).intValue();
                     ProdWert = ProdZiffern*aktZiffer;
                     ProdZiffern=ProdZiffern+ProdWert;
                     if (posGew == 3){
                       posGew=1;
                     else {
                     posGew=3;}
                     k--;
         public void init() {
                add(eingabe);
                Button b = new Button("umrechnen");
                b.addActionlistener(this);
                add(b);
                add(ausgabe);
          int PZiffer = 10 - Prodziffern % 10;
}

Answer 1

Thanks for the help. The chech digit is the last number of the ean code which is calculated and this should be compared to the entered one. Below i post the errors i get when i try to compile.
Ean1.java:15: illegal start of type
while (k>0){
Ean1.Java:9 <identifier> expected
muh = eingabe.getText();
Ean1.Java:34 <identifier> expected
int PZiffer = 10 - Prodziffern % 10;
Ean1.java: Ean1 should be declared abstract, it does not define Action Performed(java.awt.event.ActionEvent) in Ean1
public class Ean1 extends Applet implements ActionListener{
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class Ean1 extends Applet implements ActionListener{
         String muh = new String();
         TextField eingabe = new TextField(" ", 13);
         muh = eingabe.getText();
         Label ausgabe = new Label("_____");
         int k = muh.length();
         int posGew = 3;
         int ProdWert = 0;
         int ProdZiffern = 0;
         while (k>0){
                     String buchst = muh.substring(k-1,k);
                     int aktZiffer = Integer.valueOf(buchst).intValue();
                     ProdWert = ProdZiffern*aktZiffer;
                     ProdZiffern=ProdZiffern+ProdWert;
                     if (posGew == 3){
                       posGew=1;
                     else {
                     posGew=3;}
                     k--;
         public void init() {
                add(eingabe);
                Button b = new Button("umrechnen");
                b.addActionlistener(this);
                add(b);
                add(ausgabe);
          int PZiffer = 10 - Prodziffern % 10;
}